Overview

Breast cancer tumors usually start in cells in the lobules (milk-producing glands) or ducts (the pathways that move milk from the lobules to the nipple). Invasive breast cancer means it has spread from the ducts or lobules to surrounding breast tissue. Metastatic means the cancer cells have spread to distant sites in the body, such as the bones or liver.

Breast cancer types

Invasive ductal carcinoma (IDC) is the most common.

Ductal carcinoma in situ (DCIS) is non-invasive ductal cancer.

Invasive lobular carcinoma (ILC) accounts for about one in 10 invasive breast cancers.

Breast cancer facts

About 230,000 new cases are diagnosed each year, and nearly 3 million breast cancer survivors are alive in the U.S. Still, breast cancer is the second leading cause of cancer death among women. Although it occurs mostly in women, men can get it, too.

Causes of breast cancer and risk factors

The lifetime risk for women has increased from 10 percent in the 1970s to a 12.4 percent (or a 1 in 8) chance today. The strongest risk factor is aging.

Other risk factors include:

Inherited changes in certain genes, including BRCA1 and BRCA2.

Breast density. Denser breasts are at high risk.

Family history, especially if a relative was diagnosed younger than age 50.

Radiation therapy to the chest before age 30.

Age at menstruation. Have your first period before age 12 increases the risk.

Age at child bearing. Having your first child after age 35 or no childbearing boosts the risk.

Race. White women are diagnosed more often than other races, although African-American women now have about the same risks of getting diagnosed as white women but the risk of dying from the disease remains higher for African-Americans.

Controllable lifestyle factors can also increase the risk of breast cancer, such as being overweight or obese, sedentary, and drinking alcohol more than occasionally.

Prevention

There is no sure way to prevent breast cancer. Exercising four or more hours a week and keeping a normal weight can lower the risk. Having children while young and breastfeeding for long periods also reduces risk. For women at high risk, options include taking tamoxifen or other drugs to prevent breast cancer, and having surgery to remove breasts and/or ovaries.